Liquid polymers, which cure at room temperature, have become increasingly important in the manufacturing and construction industries. Among the polymers commercially available for such purpose are mercaptan terminated polymers, silane terminated polymers, isocyanate terminated polymers and epoxide terminated polymers.
Each of these polymers have certain advantages for specific applications. However, in general it may be said that the silane terminated polymers are the most desirable because they have low odor and toxicity but their relatively poor physical properties have, to a great extent, restricted their use.
It would therefore be desirable to provide liquid polymers curable to elastomeric materials which have the desirable properties of silane terminated polymers (i.e. low odor and toxicity) but at the same time cure more rapidly, have good hydrolytic stability, high tensile and tear strengths and good elongation characteristics. Others have tried to produce silane terminated polymers as, for example, the addition of silanes to isocyanate terminated polyethers as shown in U.S. Pat. No. 3,632,557 (Brode et al.) and U.S. Pat. No. 3,979,344 (Bryant et al.). Both of these patents disclose the addition of amino silanes or mercapto silanes to isocyanate terminated polyurethanes. If one used a mercapto silane, the reaction would be such that the sulfur atom would be immediately adjacent to the carbamyl group thereby forming a thiourethane group which would result in an extremely unstable polymer, particularly to water. Exposure to hot water or high humidity at moderate temperatures would cause the cured elastomers to depolymerize and form soft, tacky semisolids.
Another approach to produce silane terminated polymers is set out in U.S. Pat. No. 4,426,506 issued Jan. 17, 1984. In this patent, there is disclosed a silane terminated ureide polymer which the patent states may be made by the addition of gamma mercapto propyl trimethoxy silane to an acrylic ureide polymer. The resulting silane terminated ureide is not a rapidly curing polymer at room temperature because the sulfur atom is separated from the silicon atom by three carbon atoms.
Another patent disclosing silane terminated polymers is U.S. Pat. No. 3,317,461 issued May 3, 1967. This patent discloses silane terminated polysulfides made, for example, by reacting a mercaptan terminated polysulfide with a silane having an olefinic double bond. The polymers of this patent do not, inter alia, have high tensile and tear strengths due to the lack of urethane groups.
U.S. Pat. No. 4,652,664 discloses compounds containing silicon atoms having hydrolyzable groups. These compounds may be made by reacting a mercaptan polyhydric alcohol with a vinyl type silane. The compounds disclosed in this patent are not polymers and cannot be cured to elastomeric products. By "elastomeric", I mean a rubber having at least 100% elongation with substantially full recovery. In addition, the compounds disclosed in U.S. Pat. No. 4,652,664 have very poor shelf stability due to the ester exchange between the free hydroxyl group and the silyl group.